1. Field of the Invention
The present invention relates to an HST unit including a pair of hydraulic motor units, each hydraulic motor unit being independently arrangeable, and a hydraulic pump unit forming a traveling hydrostatic transmission in cooperation with the pair of hydraulic motor units.
2. Related Art
It has been conventionally known to form a traveling hydrostatic transmission by fluidly connecting the hydraulic pump unit and the hydraulic motor unit, which are arranged spaced apart from each other, by way of a conduit.
Such a configuration is particularly useful in a working vehicle that needs provide a space between a pair of driving wheels so as to stabilize the body posture at the time of turning such as a mower tractor capable of turning in place (zero turn) (for example, see U.S. Pat. No. 6,425,244).
However, with the conventional configuration, the hydraulic pump unit and the hydraulic motor unit have to be independently attached to the vehicle main body, and then be connected by the conduit, in the assembly work to the vehicle main body, resulting in poor assembly workability.
Furthermore, the adjustment work of the traveling hydrostatic transmission configured by the hydraulic pump unit and the hydraulic motor units is desirably performed in a state where the hydraulic pump unit and the hydraulic motor unit are fluidly connected according to the usage conditions. However, with the conventional configuration, such adjustment work can only be performed after the hydraulic pump unit and the hydraulic motor units are attached to the vehicle main body.
Furthermore, in the conventional configuration, the driving power source, which is the power source of the hydraulic pump unit, has to be attached to the vehicle main body independent from the hydraulic pump unit and the hydraulic motor units.
Moreover, in some specified cases, a reservoir tank that is an oil source of the operational fluid in the traveling hydrostatic transmission may be provided. However, with the conventional configuration, the attachment of the reservoir tank to the vehicle main body also has to be performed independent from the hydraulic pump unit and the hydraulic motor units.
In view of the conventional techniques, a first aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission.
Further, a second aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission, as well as the efficiency of the attachment work of a driving power source, which is a power source of the hydraulic pump unit, to the vehicle main body, and the efficiency of the connecting work between the power source and the hydraulic pump unit.
Furthermore, a third aspect of the present invention aims to provide an HST unit that enhances the efficiency of the conduit connecting work, the adjustment work, and the attachment work to the vehicle main body, of the hydraulic pump unit and the hydraulic motor units configuring the traveling hydrostatic transmission, as well as the efficiency of the attachment work of a reservoir tank, which is an oil source for operational fluid in the traveling hydrostatic transmission, to the vehicle main body, and the efficiency of the conduit connecting work between the reservoir tank and the traveling hydrostatic transmission.